No. III.A.] APPENDIX. 155 



lines, and a number of Haversian canals containing blood, with their series 

 of corpuscules around them. Now, if a bone has long undergone putre- 

 faction, it can be torn precisely in this manner. It will, in fact, tear to 

 shreds, and a transverse section of each of these shreds shows the Haver- 

 sian canal in the centre, and the corpuscules around it. 



The corpuscules are to be seen in every true bone of the body, and 

 form a good criterion to distinguish bone from other tissues. It is worthy 

 of remark that but little difference exists between the structure of different 

 bones, and even the intense hardness of the temporal bone immediately 

 surrounding the semicircular canals presents no microscopic difference to 

 account for that peculiarity. 



The changes which bones undergo in the interior of the earth are very 

 interesting. They may have their animal matter entire ; they may have 

 the animal matter removed; they may have the earthy matter partly 

 removed ; or, lastly, the animal matter may be carbonized. 



The bones which exhibit the animal matter entire are those which 

 have lain in certain situations not exposed to the air. I find them in this 

 state from Beg Bone Lick, in Kentucky ; and I have sections of the bones 

 of the mastodon from thence, showing the structure in the most beautiful 

 manner. Some bones found in making a sewer behind the Bank of 

 England, together with Roman sacrificial utensils, were in a similar state. 

 In both these instances, as well as in others, the Haversian canals appeared 

 to be full of black matter. 



The relation which the proportion of animal matter bears to the 

 earthy, I have examined by calcination in twenty different species. The 

 bones were all well macerated, and not greasy. The proportion in these 

 varies but little one way or another, and that more from the state of the 

 bone than anything else ; for the average is as near as possible 60 per 

 cent, of earthy material. 



When the animal matter is removed, we may always venture an opinion 

 that the bone has been imbedded in a sandy or gravelly stratum. In every 

 churchyard with this soil that I have examined, bones have been found 

 with the smallest trace of animal matter, and others not so far advanced 

 in decomposition have been noticed. Many fossil bones possess their 

 phosphate of lime, with so little animal matter as scarcely to be coloured 

 by heat. None of the bones without animal matter can by any contrivance 

 whatever be made to show the corpuscular structure, although the Haver- 

 sian canals are distinct to the naked eye, and the general appearance of 

 the bone is not materially altered, except perhaps being white, and of a 

 somewhat mineral aspect. 



The next division is that in which the animal matter is too abundant, 

 part of the earthy matter having been removed. This condition is rare, 

 and in these cases the bone will tear into shreds, each containing its 

 Haversian canal and series of corpuscules. I do not know under what 

 conditions this takes place. 



The last change is the conversion of animal matter into bitumen or 

 carbon. This change is common to the blue clay and blue lias, as here the 

 bones retain their usual quantity of phosphate of lime, but their animal 

 matter is converted into coal. This alteration appears quite unconnected 

 with heat, and takes place as a spontaneous change in a moist situation, 

 to which no air has access. I have seen different bones in every transition 



